1. Field of the Invention
The present invention relates to an ink-jet recording head device of an ink-on-demand type which mainly used for ink-jet printer.
2. Description of the Related Art
The inventor of the present invention knows an ink-jet recording head device which includes a layered product formed by laminating a plurality of plates as a main body, an ink chamber formed in the layered product, a slit formed at a front plate of the layered product, art orifice formed in a place adjacent to the front plate, and an ink conducting path formed in the layered product. The orifice is formed on the center of the slit so that the orifice is communicated with the ink conducting path through the slit.
The ink conducting path is communicated with the ink chamber, which is also communicated with an ink feeding port formed on the lower rear side of the layered product. At the back portion of the layered product, a pressure generating chamber is provided at a lower location of the orifice. The pressure generating chamber is communicated with the orifice through an ink path. The ink path is composed of two horizontal part and one vertical part and is formed like a crank.
The ink conducting path is branched into two ways, one way leading from the lower portion of the layered product to the slit directly and the other way leading from the lower portion of the layered product to the slit around the ink path.
At the rear portion of the pressure generating chamber is provided an oscillator for generating pressure. The oscillator is connected to a voltage supply. When the voltage supply applies a voltage to the oscillator, the oscillator is flexed toward the pressure generating chamber, that is, the front side. The flexing operation results in applying pressure to the ink stored in the pressure generating chamber. The pressure is communicated to the ink conductive path so that the ink is ejected from the orifice through the slit. When the voltage supply stops the application of a voltage, the flexed oscillator is restored so that the volume of the pressure generating chamber is also restored. It results in allowing the substantially same volume of ink as the ejected ink to be sucked into the ink path through the effect of the orifice.
In the ink-jet recording head device having the foregoing arrangement, however, when bubbles are entered into the pressure generating chamber or the ink path, which often takes place in this type head device, those bubbles absorb the generated pressure and thus restrict the ejection of the ink from the orifice. It results in making part of a printed character or figure thinner or lost on paper.
One of the causes why bubbles are entered into the pressure generating chamber or the ink path is that bubbles are gradually generated from the ink when using or saving the recording head device for a long time. For example, the bubbles occurring in the ink contained in the ink conducting path or the ink chamber are attached to the ink conducting path or the ink chamber as well as are flowing to the slit through the ink conducting path and the ink chamber. When the bubbles conducted to the slit are sucked to the pressure generating chamber and the ink path together with the ink when the ink contained in the slit is sucked into the pressure generating chamber. Hence, those sucked bubbles serve to absorb the pressure generated in the pressure generating chamber, resulting in preventing the ejection of the ink from the orifice. It also brings about a phenomenon that part of a character(s) or figure may be thinner or lost.